Preparation of printing surfaces for photographing



Jan. 6, 1953 G/L. MORRISON 2,624,700

PREPARATION OF PRINTING SURFACES FOR PHOTOGRAPHING Filed April 10, 1948METAL OTHER THAN 25' TYPE METAL a r V V y 59- 23 27 ELECTRO DEPOS/TEDMETAL COAT/N6 LIGHT ABSORBING 29 CORT/N6 CLEANED AND ABRADED SURFACEREADY FOR frzvenzior: George L. Morrison,

Patentecl Jan. 6, 1953 UNITED STATES PATENT OFFICE PREPARATION OFPRINTING SURFACES FOR PHOTOGRAPHIN G 4 Claims.

The present invention relates to the art of printing and is particularlyconcerned with the preparation for photographing of printing formscontaining raised or intaglio printing surfaces.

In the everyday production of certain types of gravure printingsurfaces, for example, in the practice of the photogravure androtagravure processes, the text and other material to be reproduced bythe gravure printing surface are transferred to that surface by aprocess which requires the use of a photographically produced print ortransparency of the material to be reproduced. In order to obtain such aprint or transparency, it is the usual practice to set-up a printingform containing type and/or typeslugs, and the various other printingsurfaces which are to be reproduced. This form is then inked, and animpression on paper is made therefrom. Finally, the inked imprint orimpression is photographed, and the resulting print or transparency isused in the production of the gravure surface.

There are serious disadvantages to this procedure. Regardless of howwell type, type-slugs, and printing plates are made, there is asubstantial loss in the clarity of the outlines of the printing surfacethereof during the inking and during the actual printing operation, andthis loss is carried over in any photographic operation which involvesphotographing an inked impression made from such type or other printingsurfaces. Also, the process requires careful make-ready of the form, theinking of the form, and the making of an impression on paper, all ofwhich steps involve further time and require relatively skilledworkmanship.

It is apparent that many of the difliculties inherent to the proceduredescribed above and most of the disadvantages of that procedure could beavoided by the direct photographing of the printing form, and in thepast, attempts have been made to do this. However, due at least in partto the fact that a printing form is commonly made up of elements havingvery uneven reflecting powers, varying from the high reflectance of new,cast type, or type-slugs, to the low-reflectance characteristic of, forexample, an oxidized copper plate, very poor results have been obtainedin all known direct photography procedures. In fact, the results are sounsatisfactory that the prior art has proceeded, for many years, on thetheory that the direct photography of printing forms is impractical, ifnot impossible.

The present invention, as above indicated, is

concerned with the provision of a procedure whereby it is possible todirectly photograph printing surfaces, and especially the printingsurfaces contained in the usual printing form, which may include type ofvarious kinds and varieties and. printing plates made of various metals,so as to obtain a photographic negative or positive which can be used inthe production of gravure and other printing surfaces by any of theknown methods. The invention makes possible the obtaining of a muchbetter photographic print or transparency of type and other printingsurfaces than has been possible by any of the heretofore knownprocedures. The procedure of the invention can be carried out in aminimum amount of time and with a minimum of efiort and equipment.Moreover, the practice of the invention does not impair the type orplates contained in the printing form and does not interfere with theprior or subsequent use of the form or its components for conventionalpurposes.

The features of the invention and the procedures which I prefer tofollow in practicing the, invention will be made apparent in theaccompanying drawings and in the following description of certainillustrative examples thereof. In the drawings,

Figure 1 is a perspective view of a printing form containing variouskinds of printing surfaces;

Figure 2 is a plan view of a portion of two different kinds of printingelements which may comprise a part of the printing form illustrated inFigure 1; and

Figures 3 to 6, inclusive, are sectional views, on the general line 33of Figure 2, illustrating various of the steps in the preparation of aprinting form for photographing in accordance with the invention.

The printing form illustrated in Figure 1 is of conventional type, andas such, it includes the usual heavy metal chase 9 for containing thevarious components of the form, furniture (i. e. spacers) II, and theusual locking wedges or quoins [3 for holding the printing elements inplace in the chase. As is well known in the art, the usual printing formmay include newly cast type and/or type-slugs, slightly used type, oldtype that is dirty and oxidized, photo-engravings, stereotypes, andelectrotypes and other printing plates having surfaces which may be madeof copper, zinc, brass, steel, nickel, chrome, silver, etc. The typeand/or type-slugs, and the stereotypes are all made of type metal, andthese elements alone or in combination will usually comprise the majorportion of the printing form. In the form illustrated in Figure 1, acopper printing plate is illustrated at l5, a zinc plate at IT, anelectrotype section at [8, a stereotype section at l9, and a typesection, which may be either single type and/or type-slugs, at 2|.

The manner in which the various printing surfaces contained in theprinting form are prepared for photographing, in accordance With theinvention, is illustrated particularly in Figures 2 through 6. In Figure2 there is shown a plan view of two, differing kinds of printingelements which might comprise a part of a printing form. One of these,the element 23, is made of type metal, and the other, the element 25, isa copper electro-plate which is backed with metal, or a combination ofWood and metal back, as indicated at 21. In the practice of theinvention, the process to be followed differs in one important respect,depending upon whether the printing surface to be prepared forphotographing is of a metal having high light-reflectancecharacteristics, such as type metal, or of a metal having lowerlight-reflectance characteristics, such as the metals other than typemetal in the usual type form. There are, however, only two variations inthe process. All type metal and like, high-reflectance surfaces aretreated alike, and all surfaces in the form having less inherentrefiectance than the metal of highest-reflectance capabilities, whichmetal is normally type metal, are treated alike. Hence, the two elements23 and 25, one having a type metal printing surface and the other havinga printing surface of a metal other than type metal, can be used toillustrate both of the normal variations of the invention,

As the first step in the preparation of the lower inherent reflectancesurfaces, which normally include all surfaces of metals other than typemetal, a thin coating of a metal having high actinic reflectionproperties, at least when it is polished, is applied to all suchprinting surfaces. When these non-type metal printing surfacesconstitute elements of a conventional printing form, this step ispreferably carried out when the entire form is locked-up in the chase.This coating should be very thin, prob-ably a coating of molecularthickness is sufficient, and it is most easily applied by anelectro-deposition process. For example, the coating may be applied byconnecting the negative side of a source of direct-current potential tothe printing sur face, and then rubbing the surface of the printingplate with an anode that is covered by a wick moistened with a suitableplating solution. The operation takes but a minute or two to accomplish,and the metallic coating is applied only to the actual printing surfaceas illustrated at 29 in Figure 4.

A number of metals can be used for the high reflectance coating which isapplied to the printing surfaces, which are not of type metal. Theseinclude tin, cadmium, silver, and other of the white metal group,although the use of tin is particularly preferred since this metal seemsto produce a much better surface than any of the other metals.

After the formation of this high-reflectance, metallic coating on allprinting surfaces which are of a metal other than type metal, theprocess of the invention is the same for all of the components of theprinting form. As the next step, the entire form is coated with alight-absorbing or non-actinic coating, preferably by spraying, althoughthis coating can be applied in any other manner, This overallnon-reflecting coating, as initially applied, is illustrated at 3| inFigure 5. Various materials can be used for the lightabsorbing coating 3I; the best coatings, however, are those which include a suitablelight-absorbing pigment dispersed in a suitable liquid vehicle whichcontains a binder for the pigment. The sprayed coating should dryrapidly and should be readily removable from the printing surfaces, asis required in the next step of the preparation procedure; it shouldalso be readily removable from all other parts of the printing form atthe conclusion of the photographing operation. At the same time, thecoating should not dust or crack, and it should not be toxic or dimcultto use.

A particularly satisfactory coating is produced by the mixture of fourparts of water, one part of liquid soap (desirably a slightly acid,cocoanut oil soap) and three parts of dry, drop-black pigment, all partsbeing by volume. This coating should be mixed daily; it is water solubleand hence is very easily removed from the type and printing platesurface. Also, the material does not dust; it is cheap, easy to handle,and noncracking.

It will be understood, however, that other types of coatings can beused. The essential thing is the provision of a coating which will notreflect actinic light. For example, it is possible to employ analcohol-base coating, a suitable formula including one part shellac, sixparts dry, drop-black, and eight parts methanol, all by volume. Thiscoating dries very fast, but in order to make possible convenientremoval of the coating from the printing surfaces which are to bephotographed, it is necessary to ink the printing form before thecoating is applied, as will be hereinafter described. It is alsopossible to use coatings which comprise dispersions of pigments otherthan drop black, for example, red lead can be used quite successfully.Also, it is possible to spray the printing form with an optical blacklacquer, but materials of this type are recommended, due to thedifficulties experienced in cleaning the type and other components ofthe printing form.

After the non-reflecting coating which has been applied to the entiresurface of the printing form has dried, that coating is removed from theprinting surfaces only of the various printing elements making up theform. The non-reflecting coating which remains thus masks or covers theentire background of the printing form, as illustrated at 3la in Figure6, at the same time the metallic printing surfaces are completelyexposed.

The removal of the non-reflecting coating from the printing surfaces isconveniently accomplished by the use of a cloth-covered, rather firm,rubber block, or equivalent means. If the coating has been applied bythe use of the watersoap-pigment mixture described above, theclothcovered pad may be used dry and a few light strokes of the pad willeffect adequate cleaning of the printing surfaces. If an alcohol typecoating is used, the printing form should be inked preliminary to theapplication of the coating, and the coating can be removed by using apad which has been moistened in naphtha, benzene or other ink solvent.

After the non-reflecting coating has been removed from the printingsurfaces, those surfaces are very clearly visible in the face of theform, the remaining coating providing a light-absorbing background whichoutlines the printing surfaces. However, it is not yet possible tosatisfactorily photograph these surfaces, and as the final step in thepreparation of printing surfaces in accordance with the invention, theprinting surfaces constituting the form are subjected to an abrasivetreatment which performs the dual function of cleaning the printingsurfaces and converting those surfaces into a substantially uniformmatte finish, which is a diffusively refiecting surface fine enough topermit a high percentage of incident light to obey the cosine law. Theabrading can be accomplished in various ways, but particularlysatisfactory results are had when the abrading is accomplished by theuse of a block of rubber or rubber-like compound containing very fineabrasive material. An ordinary pencil eraser is an example of suchmaterial, although a larger block such as is commonly used in thejewelry and metal-polishing industries will be found more practical incommercial operations. The abrasive material contained in the block ispreferably very fine, such as fiour of emery, diatomaceous earth, andthe like. The abrading removes dirt, ink, oxides and the like andconverts the printing surfaces in the form to clean, matte surfaceshaving uniform light-diffusion properties, and for best results theabrasive-produced matte surface should not contain any lines largeenough to be visible to the naked eye. A few light strokes of theabrasive-carrying block across the printing surfaces in the form areusually sufficient to produce the desired result. Thus the combinationabradin and cleaning operation, similar to the other steps of theprocess, may be accomplished in a very short interval of time.

Upon the completion of the abrasion operation the form is ready forphotographing. This may be efiected by the use of an ordinaryphotoengraving camera, or otherwise. As pointed out in my co-pendingapplication, Serial No. 63,037, which was filed on December 2, 1948,certain specialized illumination procedures are of particular advantagein photographing printing forms and other printing surfaces which mayhave been prepared as above described. After the form has beenphotographed, the background coating should be removed as by washingwith water or a solvent.

The form may then be used for printing or for making stereotypes in theusual manner, or the form may be disassembled.

In the foregoing there has been described a new and improved method forpreparing printing surfaces for photographing, and especially forpreparing for photographing the various relief printing surfacescontained in the usual printing form. In the practice of the invention,if the printing form contains printing surfaces of metals other thantype metal, as is usual in the printing industry, those surfaces arefirst provided with a very thin coating of a white metal, preferablytin; next the entire form is sprayed with a non-reflecting coating andthis coating is removed from the printing surfaces only by rubbing theform with a cloth covered pad or the like. Finally, a uniform, clean,diffusively refleeting surface is created on all of the printingsurfaces in the form by the use of a very fine abrasive, or by anequivalent procedure; this matte surface can be photographed to providea uniform density, sharp outline print or transparency of the printingsurfaces contained in the form.

The practice of the invention does not in any way impair printingsurfaces on which it is used or prevent the subsequent use of suchsurfaces in ordinary printing operations. The procedure of the inventioncan be carried out rapidly and economically. At the same time, however,it provides a much higher quality print or transparency .than hasheretofore been available in the printing art. Various of the featuresof the invention believed to be new are set forth in the appendedclaims.

I claim:

1. The method of preparing for photographing a printing form containingprinting surfaces of type metal and printing surfaces of at least onemetal other than type metal, which comprises the steps of electroplatingonto the printing surfaces which are of a metal other than type metal, avery thin coating of a metal which when clean and polished has lightreflecting properties approximately equal to clean, polished type metal,applying a light-absorbing coating to the entire surface of the printingform, removing said coating from the relief surfaces, while leaving thecoating intact on the other surfaces of the form, and abrading saidrelief printing surfaces to produce thereon a clean, diifusivelyreflecting finish of sufficient fineness that the individual lines inthe surface are not visible to the naked eye.

2. The method of preparing for photographing a printing form containingprinting surfaces of type metal and printing surfaces of at least onemetal other than type metal, which comprises the steps of electroplatinga very thin coating of tin onto the printing surfaces which are of ametal other than type metal, coating the entire surface of said printingform with a light-absorbing coating, removing said coating from therelief printing surfaces, while leaving the coating intact on the othersurfaces of the form, and abrading said relief surfaces to providethereon a clean, diffusively reflecting finish of sufficient finenessthat the individual lines in the surface are not visible to the nakedeye.

3. The method of preparing for photographing a printing form containingprinting surfaces of type metal and printing surfaces of at least onemetal other that type metal, which comprises the steps of electroplatinga thin coating of a metal which when clean and polished has lightrefiecting properties approximately equal to clean, polished type metalonto the printing surfaces which are of a metal other than type metal,applying a mixture of water, liquid soap and a light absorbing pigmentto the entire surface of the printing form, thereby providing anon-dusting light-absorbing coating on the entire surface of the form,removing the coating so provided from the relief printing surface whileleaving the coating intact on the other surfaces of the form, andfinally treating said relief surfaces by the use of a resilient blockcontaining an abrasive of such fineness that there is produced thereon aclean, diffusely reflecting finish of sufficient fineness that theindividual lines in the surface are not visible to the naked eye.

4. The method of preparing for photographing a printing form containingprinting surfaces of type metal and printing surfaces of at least onemetal other than type metal, which comprises the steps of electroplatinga very thin coating of high reflecting metal selected from the groupin-v REFERENCES CITED The following references. are of record in thefile of this patent:

UNITED STATES PATENTS Name Date Aylsworth June 2, 19 14 Number Number.

Number Name Date Austin June28, 1921 Stafford Nov. '7, 1922 Grass May15, 1928 De Goyer Aug. 15, 1933 Hetherington July 23, 1935 Thomson June8, 1937 Jenney et. a1. Aug. 9, 1938 Keuffeletlal. Aug. 1, 1946 Witchgerl Sept. 2, 1947 Alger: -4 Dec. 21, 1948 FOREIGN PATENTS Country DateGreatBritaln Nov; 16, 1933 OTHER REFERENCES Clerc llford Manual, pub. byIlford Lmtd., London, 1946, page 244.

1. THE METHOD OF PREPARING FOR PHOTOGRAPHING A PRINTING FORM CONTAININGPRINTING SURFACES OF TYPE METAL AND PRINTING SURFACES OF AT LEAST ONEMETAL OTHER THAN TYPE METAL, WHICH COMPRISES THE STEPS OF ELECTROPLATINGONTO THE PRINTING SURFACES WHICH ARE OF A METAL OTHER THAN TYPE METAL, AVERY THIN COATING OF A METAL WHICH WHEN CLEAN AND POLISHED HAS LIGHTREFLECTING PROPERTIES APPROXIMATELY EQUAL TO CLEAN, POLISHED TYPE METAL,APPLYING A LIGHT-ABSORBING COATING TO THE ENTIRE SURFACE OF THE PRINTINGFORM, REMOVING SAID COATING FROM THE RELIEF SURFACES, WHILE LEAVING THECOATING INTACT ON THE OTHER SURFACES OF THE FORM, AND ABRADING SAIDRELIEF PRINTING SURFACES TO PRODUCE THEREON A CLEAN, DIFFUSIVELYREFLECTING FINISH OF SUFFICIENT FINENESS THAT THE INDIVIDUAL LINES INTHE SURFACE ARE NOT VISIBLE TO THE NAKED EYE.